Monocytes are a type of white blood cell that originate from myeloid progenitors in bone marrow. From there they enter the peripheral blood stream and later migrate into tissues. In the tissues, after exposure to local growth factors, pro-inflammatory cytokines, and microbial compounds, monocytes differentiate into macrophages and dendritic cells. Macrophages derived from monocyte precursors undergo specific differentiation into the classically polarized (M1) macrophages and the non-classically activated (M2) macrophages. Normally, macrophages serve three main functions in the immune system. These are phagocytosis, antigen presentation, and cytokine presentation. In addition, certain types of cancers (such as, for example, breast cancer, astrocytoma, head and neck squamous cell cancer, papillary renal cell carcinoma Type II, lung cancer, pancreatic cancer, gall bladder cancer, rectal cancer, glioma, classical Hodgkin's lymphoma, ovarian cancer, and colorectal cancer) exhibit elevated levels of M2-like macrophages within the tumor and similar M2 monocytes circulating in the periphery. Despite advances in cancer therapy, the prognosis for these cancers remains poor and attempts to treat these cancers using conventional treatments such as, for example, chemotherapy, external beam radiation, and brachytherapy have led to only marginal improvements in progression-free survival and overall survival. Therefore, there is a need in the art to obtain new and improved treatments for such cancers.